Light Receiving Element Layout for Pixel Edge Light Leakage
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Solution Overview
Problem
In imaging elements and distance measuring devices, incident light from the edges of pixel regions mixes with adjacent pixels, causing noise such as flare and deteriorating image quality, and avalanche photodiodes are prone to malfunction due to leakage from dummy pixels.
Innovation Solution
A light receiving element design featuring a pixel region with photodiodes and an on-chip lens, along with an adjacent pixel having an on-chip lens with different curvature or a semiconductor region light-blocking wall to prevent light leakage, and varying wiring layer configurations to reduce reflection and crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If dummy pixels are arranged between the pixel region and end portion to ensure uniformity, then pixel uniformity is improved, but light leakage and noise occur
Solution Approach 1:
The patent divides the semiconductor substrate into distinct functional regions: a pixel region with pixels having the same configuration, and an adjacent pixel region with pixels having different configurations. This segmentation allows dummy pixels to be separated from the main pixel region, preventing light leakage while maintaining uniformity in the pixel region.
Solution Approach 2:
The patent applies local quality by making pixels in the adjacent pixel region have different configurations from pixels in the main pixel region. Specifically, pixels adjacent to the pixel region are configured differently to prevent them from receiving incident light, while pixels in the main pixel region maintain their standard configuration for proper image sensing.
2Measurement precision
If avalanche photodiodes are used to improve sensitivity, then detection sensitivity is improved, but malfunction occurs due to leakage from dummy pixels
Solution Approach 1:
The patent segments the substrate into pixel regions and adjacent pixel regions, isolating avalanche photodiodes in the main pixel region from potential light leakage sources in the adjacent pixel region. This spatial segmentation protects the sensitive avalanche photodiodes from malfunction while preserving their high detection sensitivity.
Solution Approach 2:
The patent implements preliminary anti-action by configuring adjacent pixels differently before light can leak into the main pixel region. This preventive configuration blocks potential light leakage paths before they can reach the avalanche photodiodes, preventing malfunction before it occurs.
3Use of energy by moving object
If on-chip lens is arranged close to semiconductor substrate to improve light focusing, then light focusing ability is improved, but crosstalk and color mixing occur
Solution Approach 1:
The patent segments pixels with on-chip lenses from adjacent pixels without proper lens configuration by creating distinct pixel regions and adjacent pixel regions. This segmentation prevents oblique light from adjacent pixels from reaching the on-chip lens, eliminating crosstalk and color mixing while maintaining effective light focusing.
Solution Approach 2:
The patent applies local quality by providing on-chip lenses only in the main pixel region where they are needed for focusing incident light, while adjacent pixels have different configurations that prevent them from contributing to crosstalk. This localized approach maintains focusing ability where needed while preventing harmful effects.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively blocks incident light from adjacent pixels, reducing noise and improving image quality by focusing light on different positions and adjusting light focusing, thereby preventing malfunctions in avalanche photodiodes.
Implementation Method 1
a photodiode formed on a semiconductor substrate in which a charge generated by photoelectric conversion of incident light is multiplied with a high reverse bias voltage
Implementation Method 2
a photodiode formed on a semiconductor substrate in which a charge generated by photoelectric conversion of incident light is multiplied with a high reverse bias voltage
Implementation Method 3
an on-chip lens that focuses the incident light on the photodiode
Data Source
AI summary
To prevent leakage of incident light from pixels around a pixel region (11) of a light receiving element. A light receiving element includes a pixel region and an adjacent pixel (400). In the pixel region, a plurality of pixels (100) is arranged, the plurality of pixels including a photodiode formed in a semiconductor substrate (110) in which a charge generated by photoelectric conversion of incident light is multiplied with a high reverse bias voltage, an on-chip lens (160) that focuses the incident light on the photodiode, and a wiring region (120) having a wiring layer (122) connected to the photodiode and an insulating layer (121) that insulates the wiring layer. The adjacent pixel is arranged adjacent to the pixel region and includes the photodiode, an on-chip lens (161) having a curvature different from a curvature of the on-chip lens, and the wiring region.